/Engine/Source/Runtime/Landscape/Public/LandscapeEdit.h
Updates weightmap for LayerInfo, optionally adjusting all other weightmaps.
void SetAlphaData ( [ULandscapeLayerInfoObject](API\Runtime\Landscape\ULandscapeLayerInfoObject) * LayerInfo, const int32 X1, const int32 Y1, const int32 X2, const int32 Y2, const uint8 * Data, int32 Stride, ELandscapeLayerPaintingRestriction PaintingRestriction, bool bWeightAdjust, bool bTotalWeightAdjust )